Pattern is by default a normal string that is matched precisely (but without
regard to case, except in the case of pickaxe). However, when you check the re checkbox,
the pattern entered is recognized as the POSIX extended
regular expression (also case
insensitive).

commit

The commit messages and authorship information will be scanned for the given pattern.

grep

All files in the currently selected tree (HEAD unless you are explicitly browsing
a different one) are searched for the given pattern. On large trees, this search can take
a while and put some strain on the server, so please use it with some consideration. Note that
due to git-grep peculiarity, currently if regexp mode is turned off, the matches are
case-sensitive.

author

Name and e-mail of the change author and date of birth of the patch will be scanned for the given pattern.

committer

Name and e-mail of the committer and date of commit will be scanned for the given pattern.

pickaxe

All commits that caused the string to appear or disappear from any file (changes that
added, removed or "modified" the string) will be listed. This search can take a while and
takes a lot of strain on the server, so please use it wisely. Note that since you may be
interested even in changes just changing the case as well, this search is case sensitive.